Inverse acoustical characterization of porous media

Ali Hamoudi, Raymond Panneton

Abstract

A six-parameter model by Johnson Lafarge is used to focus the inversion acoustical characterization of porous media. The model is used to describe the viscous and thermal dissipations of acoustic waves in the porous material. The six macroscopic parameters of the model are open porosity, static airflow resistivity, tortuosity, viscous characteristic dimension, thermal characteristic dimension, and static thermal permeability. The material can be modeled as an equivalent fluid under acoustical excitations if the frame of the porous material is assumed motionless. This equivalent fluid is described by its dynamic density and dynamic bulk modulus. Both dynamic properties are related to the macroscopic parameters of the material and depend on the frequency of excitation.